The Candela VibroPhase is the world's first candle-powered guitar effect. Designed for fans of the 1800s, guitar effects enthusiasts who have to have everything, and guitarists who want a wildly more adjustable take on the Univibe than has ever been created before. The sound sweeps from subtle vibrato to Leslie-like phasing with a speed range wider than anything ZVEX has ever produced. There are two gear ratios on the Stirling engine that cover about a 20:1 speed range when used with the eddy current brake, which is a 1" diameter neodymium sphere magnet. You can paint your own modulation patterns on the interchangeable optical control discs, which quickly pop in and out of the machine, so you can create your own LFO wave shape and rhythm. 

Data Sheet and Technical Specifications

Background and Development

The Candle 

There's a tea light candle that powers the Candela in three ways. Naturally it gets very hot, about 1400°C/2500°F, so don't start a fire and keep children and animals away. It burns for 4-5 hours for around 8.3 cents per unit. So over the course of 37 years, if you play for 10 hours a day, your Candela VibroPhase will pay for itself in battery savings alone. 

Solar Cells 

Two solar cells illuminated by the candle produce 9 volts for the effect's electronics, at 0.33mA. That's right, one massive third of a milliamp. If a little room light leaks onto the cells that certainly doesn't hurt, but it actually works perfectly well in complete darkness and is generally unaffected by a little Cuban cigar smoke, now that they're legal again. I think. 

Stirling Heat Engine 

The Stirling engine provides mechanical power from the heat of the candle. It has a glass bulb that takes heat from the flame and it spins round and round, via some inexplicably beautiful to watch magic. That wonderful machine was designed by the Stirling brothers in 1816 and, although they died penniless, it's incredibly sexy and it does a great job of spinning the optical disk. 

The Spherical Magnet 

There's a wonderful speed control on the Stirling engine that uses force at a distance, one of my favorite things, via eddy currents generated in the engine's flywheel by a powerful adjustable magnet. By swinging the magnet toward the edge of the flywheel, the engine slows down dramatically as power is generated inside it that creates an opposing magnetic field. It's pretty strange because the magnet does not stick to the brass and gold flywheel. 

The Optical Disc 

The optical disc is a plastic circle with a pattern painted on it or taped to it. The pattern can be any shape. For my first shape I chose an offset circle, which created a pleasing asymmetrical pulsation. It can be anything, really, like spokes or waves or a gradient created with an airbrush, or even polarizing plastic sheet, which can be purchased for iPhone repair. 

The Electronics Package 

The black tube on it's own stand is where the Vibrophase effect is located. It has a rotating neutral density filter mounted on the front which lets you set the overall brightness going into the electronics package, to center the way the Vibrophase's sound moves around. The light from the candle that passes through the optical disk and shines on the circuit's photocells is what modulates the vibrato/ phaser circuit. There are two cloth-covered wires passing from the solar cells on one side of the candle to the binding posts on the back of the electronics tube. 

Operation 

Most adjustments are done via the little levers. Get to know where all of them are and what they do. 

When you first fire up the candle you have to adjust its height to about 1/8" away from the glass cylinder on the Stirling engine, about 3/4" in from the end, but if it's a little too high all that will happen is soot will collect on the tube. It wipes right off when it's cooled down. Once the position of the candle is set, you can manually spin the flywheel to get it going. Adjust the magnet away to get the speed up at first. Once it's spinning, you can engage the optical disk to get that spinning. Depending on the speed range you choose, which is selected by using the outside of the flywheel for high and the little pulley for low, you'll have to adjust the arms holding the disc so that the light passing through the disc lands exactly on the photocells. You can look through the disc to see this, somewhat. It takes a bit of gymnastics to get it all tweaked up the first time, but that's part of the fun. It's easiest to move the electronics package out of the way and look through the disc at the candle, watching for the light modulation as the disc spins around, until you can see the flame alternately disappear and reappear. Then move the black tube back into place. 

Usually the height of the black tube is right when it's just about to touch the lollipop end of the disc arm. Make sure that the end of the black tube is rotated correctly for the speed… usually 45° lines up well for high speed, and horizontal for low speed. The whole front of the tube rotates pretty easily. Be careful to set the filter to the most open position (there's a scale printed on it that makes it easy). 

Now you need to get the solar cells in place. They swing over and, by lifting their mounting rod up with the tip of one finger under the swinging arm, they sit on the edge of the candle holder right up against the candle and black tube. The most power is generated when they're sitting exactly at candle level right on the brass shelf. 

Plug the send/return cable into the foot switch pedal and your guitar and amp into it as well. The foot switch pedal contains a true bypass switch, one TRS jack for the Candela Vibrophase, and an input and output jack. There's no LED… the solar cells can't provide enough power for that. I may eventually install another candle in the foot switch for an indicator and foot-warmer. ;) 

Take a listen. When the knob on the black tube is turned clockwise it reaches a peak phaser sound that will, when perfectly set, make the speaker cabinet sound like it's moving around the room and spinning. When counter-clockwise the knob is adjusted for gentle vibrato (varying pitch). The most dramatic phaser sound has elements of wah, phase, leslie and tremolo at once. Adjust the magnet for your favorite speed. 

Eventually the candle will burn down far enough to begin to affect the performance. Unlike a battery, this is no problem. Just swing the solar cells out of the way and readjust the candle's height, being careful not to spill wax all over the place with sudden movements. Make sure it's centered on the glass cylinder and the tip of the flame is roughly 1/8" from the glass, with the flame located about 3/4" in from the tip. Surprisingly, the exact position of the candle isn't incredibly critical for the Stirling engine, but it is important to get it to shine through the disc correctly. 

If there's a breeze in your performance area you'll need to use the vented glass cloche to cover the unit while it's operating. This will stabilize the speed and will give you the longest candle life. The best tea light candles have clear plastic cups so that the light shines through as they get low. Dollar General sells them 12 for a buck and Amazon has lots of choices. They're generally available at a lot of grocery stores and pharmacies too. Contact me for my current favorite brand. 

Warning: Because this unit uses an actual flame, there is a risk of fire and burns. Keep away from children and pets. Do not allow children to operate. Wait until glass is cool before touching or cleaning the Stirling engine. Clean with a soft tissue or paper towel. Do not use abrasives on glass. Candle takes several minutes to cool. Seriously. Hot wax may burn and leave stains or marks on everything you love, so take your guitar off when changing candles. If you're in a hurry, set an ice cube in the candle. There's probably one in your drink. Do not spill wax on crotch. Wax may be removed from clothing using an iron through paper towels, no steam. (I learned this the hard way.) REMOVE PANTS BEFORE IRONING. Clean iron thoroughly after it cools. 

Enjoy! 

Zachary Vex 2.18.2016

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